This invention relates to novel membrane compositions. In particular this invention relates to membranes comprising at least one layer which can be prepared by reaction of a polymer derived from a hydroxyalkyl methacrylate and a polymer derived from a vinylaralkyl dialkylsulfonium salt.
The prior art discloses a variety of membranes useful in reverse osmosis. Cellulose acetate membranes, as described in U.S. Pat. Nos. 3,133,132 and 3,133,137, have been used in commercial desalination operations. U.S. Pat. No. 3,567,632 describes certain aromatic polyamide membranes. More recently, composite membranes have been the object of considerable research. See, e.g., U.S. Pat. Nos. 4,005,012, 4,039,440 and 4,277,344.
European Patent Application No. 26,576 describes membranes obtained by crosslinking methylolated vinylphenol polymers These membranes are reported to have excellent water flux, solute rejection and chemical resistance.
In general all of the aforementioned membranes are deleteriously affected if chlorinated water is employed as feed. This frequently necessitates the costly pretreatment of feed water to reduce the chlorine species present to a concentration which will not deleteriously affect the membrane (usually less than 0.1 part per million by weight). Consequently, it would be desirable to develop membrane compositions which offer greater tolerance of chlorine in the water.